US7768431B2 - R/D converter and angle detecting apparatus - Google Patents
R/D converter and angle detecting apparatus Download PDFInfo
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- US7768431B2 US7768431B2 US12/317,095 US31709508A US7768431B2 US 7768431 B2 US7768431 B2 US 7768431B2 US 31709508 A US31709508 A US 31709508A US 7768431 B2 US7768431 B2 US 7768431B2
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- 238000001514 detection method Methods 0.000 claims abstract description 38
- 230000005284 excitation Effects 0.000 claims abstract description 33
- 230000001360 synchronised effect Effects 0.000 claims abstract description 31
- 230000008030 elimination Effects 0.000 claims abstract description 17
- 238000003379 elimination reaction Methods 0.000 claims abstract description 17
- 230000000694 effects Effects 0.000 claims description 10
- 238000000034 method Methods 0.000 description 3
- 230000008878 coupling Effects 0.000 description 1
- 238000010168 coupling process Methods 0.000 description 1
- 238000005859 coupling reaction Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
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Classifications
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03M—CODING; DECODING; CODE CONVERSION IN GENERAL
- H03M1/00—Analogue/digital conversion; Digital/analogue conversion
- H03M1/06—Continuously compensating for, or preventing, undesired influence of physical parameters
- H03M1/08—Continuously compensating for, or preventing, undesired influence of physical parameters of noise
- H03M1/0827—Continuously compensating for, or preventing, undesired influence of physical parameters of noise of electromagnetic or electrostatic field noise, e.g. preventing crosstalk by shielding or optical isolation
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03M—CODING; DECODING; CODE CONVERSION IN GENERAL
- H03M1/00—Analogue/digital conversion; Digital/analogue conversion
- H03M1/12—Analogue/digital converters
- H03M1/48—Servo-type converters
- H03M1/485—Servo-type converters for position encoding, e.g. using resolvers or synchros
Definitions
- the present invention relates to an R/D converter that converts a resolver signal output from a resolver, which detects the angle of rotation of a motor, into a digital angle signal (digital angle output), and an angle detecting apparatus having the R/D converter.
- the method described in the patent literature 1 assumes that the motor line for supplying the motor current to the motor and the resolver line for drawing the resolver signal from the resolver that detects the angle of rotation of the motor are disposed in parallel with each other.
- the magnetic field produced around the motor line by the motor current traverses the resolver line to cause induced noise simultaneously in both the first and the second signal as differential signals.
- a common mode filter is disposed in the input stage of the R/D converter.
- the resolver is disposed close to the motor. Accordingly, the resolver is strongly affected by the magnetic field produced by the motor, and noise due to the magnetic field produced by the motor is superposed on the resolver signal.
- the motor is rotating, the magnetic field produced by the motor is in synchronization with the rotation of the motor. Therefore, the superposed noise due to the magnetic field produced by the motor is low-frequency noise.
- the noise is normal mode noise and therefore cannot be eliminated by the common mode filter described above.
- a basic configuration of the RID converter is disclosed in the patent literature 2 (Japanese Patent No. 3442316, Japanese Patent Application Laid-Open No. 2000-353957). However, the patent literature 2 makes no reference to removal of noise.
- An object of the present invention is to provide an R/D converter capable of eliminating or reducing normal mode noise caused by a magnetic field produced by a motor and thereby reducing an output angle error, and an angle detecting apparatus having the R/D converter.
- noise superposed on a resolver signal by the effect of a magnetic field produced by a motor has been analyzed. Then, it has been found that a noise component in the signal output from a synchronous detector has a peak in the vicinity of the frequency of the excitation signal. Thus, means of eliminating or reducing the noise component is provided in an R/D converter.
- FIG. 1 is a block diagram showing a configuration of an R/D converter and an angle detecting apparatus according to an embodiment of the present invention
- FIG. 2 is a graph showing waveforms of resolver signals S 1 and S 2 ;
- FIG. 3 is a graph showing a waveform before synchronous detection
- FIG. 4 is a graph showing waveforms before and after synchronous detection
- FIG. 5 is a graph showing frequency components of a waveform after synchronous detection
- FIG. 6 is a graph showing a waveform before and after filtering.
- FIG. 7 is a graph showing an output angle error of the R/D converter.
- FIG. 1 shows an example of the configuration of an R/D converter according to an embodiment of the present invention together with a motor, a resolver, and an excitation signal generating part.
- a resolver 10 is of the one-phase-excitation/two-phase-output type and is disposed close to a motor 20 .
- a first resolver signal S 1 and a second resolver signal S 2 output from the resolver 10 are input to an R/D converter 30 .
- an excitation signal is input from an excitation signal generating part (ESGP) 40 to the resolver 10 and the R/D converter 30 .
- ESGP excitation signal generating part
- the resolver 10 has an excitation signal application coil, a first detecting coil and a second detecting coil.
- An excitation signal (sin ⁇ t) applied to the excitation signal application coil induces a first resolver signal S 1 (cos ⁇ sin ⁇ t) and a second resolver signal S 2 (sin ⁇ sin ⁇ t), which are modulated in amplitude, in the first detecting coil and the second detecting coil according to the angle of rotation ⁇ of a rotor of the motor 20 from a predetermined reference position (that is, a detection angle ⁇ ) because of magnetic coupling in the resolver, respectively.
- the resolver signals S 1 and S 2 have amplitudes of cos ⁇ sin ⁇ t and sin ⁇ sin ⁇ t, respectively, and the amplitude of the resolver signals varies with a change of the rotation angle ⁇ .
- the R/D converter 30 has a first multiplier 31 , a second multiplier 32 , a subtracter 33 , a synchronous detection circuit (SDC) 34 , a band elimination filter (BEF) 35 , a controller 36 , a SIN ROM 37 , and a COS ROM 38 .
- the R/D converter 30 has an angle calculation loop, in which an output ⁇ of the controller 36 is applied to the first multiplier 31 and the second multiplier 32 via the SIN ROM 37 and the COS ROM 38 , respectively, converts the detection angles ⁇ implied in the resolver signals S 1 and S 2 into the digital angle output ⁇ , and outputs the digital angle output ⁇ .
- the SIN ROM 37 in the R/D converter 30 produces a sine value sin ⁇ from the digital angle output ⁇ and outputs the sine value sin ⁇ to the multiplier 31 .
- the COS ROM 38 produces a cosine value cos ⁇ from the digital angle output ⁇ and outputs the cosine value cos ⁇ to the multiplier 32 .
- the multiplier 31 multiplies the resolver signal S 1 by the sine value sin ⁇ and outputs the product to the subtracter 33
- the multiplier 32 multiplies the resolver signal S 2 by the cosine value cos ⁇ and output the product to the subtracter 33
- the subtracter 33 subtracts the output of the multiplier 31 from the output of the multiplier 32 and outputs the difference to the synchronous detection circuit 34 .
- the synchronous detection circuit 34 performs synchronous detection of the output of the subtracter 33 by referring to the excitation signal input from the excitation signal generating part 40 and outputs the detected output to the band elimination filter 35 in this example.
- the detected output having passed through the band elimination filter 35 is input to the controller 36 , and the controller 36 adjusts the digital angle output ⁇ to make the detected output zero, or in other words, to make the deviation sin( ⁇ ), which is the detected output, zero.
- the controller 36 is the same as the compensator 56 and the 12-bit counter 57 described in the patent literature 2, for example. That is, when the deviation sin( ⁇ ) is not equal to zero, the digital angle output ⁇ is adjusted to bring the deviation sin( ⁇ ) close to zero, thereby converting the detection angle ⁇ into the digital angle output ⁇ .
- the controller 36 see the patent literature 2, for example.
- the excitation signal output from the excitation signal generating part 40 is denoted by sin ⁇ t
- an angular frequency of the excitation signal is denoted by ⁇
- the detection angle of the resolver is denoted by ⁇
- the angular frequency of the noise due to the magnetic field produced by the motor 20 is denoted by ⁇ ′.
- the first term sin( ⁇ t ⁇ ) sin ⁇ t in the formula (3) is the component essential for angle calculation, and the second term cos ( ⁇ ′t+ ⁇ ) is the noise component.
- the angular frequency ⁇ ′ of the noise due to the magnetic field produced by the motor 20 is equal to the rotational angular frequency of the motor 20
- FIG. 2 is a graph illustrating the resolver signals S 1 and S 2 expressed by the formulas (1) and (2) affected by the magnetic field produced by the motor 20 in a case where the frequency of the excitation signal sin ⁇ t is 10 kHz, and the rotational frequency of the motor 20 is 500 Hz.
- the thick line indicates the resolver signal S 1
- the thin line indicates the resolver signal S 2 .
- FIG. 3 shows a waveform of a signal yet to be subject to synchronous detection expressed by the formula (3) (that is, a waveform of the output of the subtracter 33 ) in a case where the resolver signals S 1 and S 2 shown in FIG. 2 are input to the RID converter 30 .
- FIG. 3 shows a waveform of a signal yet to be subject to synchronous detection expressed by the formula (3) (that is, a waveform of the output of the subtracter 33 ) in a case where the resolver signals S 1 and S 2 shown in FIG. 2 are input to the RID converter 30 .
- FIG. 3 shows a
- FIG. 3 also shows a waveform in a case where the magnetic field produced by the motor 20 has no effect on the resolver signals.
- the thin line indicates the waveform in the case where the magnetic field produced by the motor 20 has an effect on the resolver signals
- the thick line indicates the waveform in the case where the magnetic field produced by the motor 20 has no effect on the resolver signals.
- FIG. 4 shows a waveform before synchronous detection in the case where the magnetic field has an effect shown in FIG. 3 and a waveform after synchronous detection using the excitation signal sin ⁇ t.
- the thick line indicates the waveform before synchronous detection
- the thin line indicates the waveform after synchronous detection.
- FIG. 5 shows frequency components of the waveform after synchronous detection shown in FIG. 4 .
- the waveform after synchronous detection has peaks at frequencies of 10 kHz ⁇ 1 kHz. Therefore, if the band elimination filter 35 having a center frequency of 10 kHz, which is the frequency of the excitation signal, is inserted behind the synchronous detection circuit as shown in FIG. 1 , the noise component expressed by the second term of the formula (3) can exclusively suppressed.
- the bandwidth of the band elimination filter 35 is equal to or higher than 2 kHz and equal to or lower than 10 kHz.
- the noise after synchronous detection has peaks at an angular_frequency equal to the angular_frequency ⁇ of the excitation signal sin ⁇ t plus the angular frequency 2 ⁇ that is double the rotational angular frequency ⁇ of the motor 20 and an angular frequency equal to the angular frequency ⁇ of the excitation signal sin ⁇ t minus the angular frequency 2 ⁇ that is double the rotational angular frequency ⁇ of the motor 20 . Therefore, as illustrated in FIG.
- the noise after synchronous detection has peaks at a frequency equal to the frequency ⁇ /(2 ⁇ ) of the excitation signal sin ⁇ t plus the frequency 2 ⁇ /(2 ⁇ ) that is double the rotational frequency ⁇ /(2 ⁇ ) of the motor 20 and an frequency equal to the frequency ⁇ /(2 ⁇ ) of the excitation signal sin ⁇ t minus the frequency 2 ⁇ /(2 ⁇ ) that is double the rotational frequency ⁇ /(2 ⁇ ) of the motor 20 .
- the band elimination filter 35 may be any filter that can eliminate or reduce the noise in a band in the vicinity of the frequency of the excitation signal and does not affect the characteristics of the angle calculation loop.
- the band of the band elimination filter 35 is determined to include the two peaks of the noise after synchronous detection described above.
- the bandwidth of the band elimination filter 35 is determined to be equal to or higher than 4 ⁇ (2 ⁇ 2 ⁇ ) and not to overlap the band of the angle calculation loop, that is, the band of the deviation sin( ⁇ ).
- the band elimination filter 35 may be a notch filter if the Q value of the filter is appropriately selected.
- FIG. 6 shows a waveform of the signal having passed through the band elimination filter 35 in a case where the band elimination filter 35 is a notch filter having a center frequency f n of 10 kHz and a Q value of 1 together with the waveform after synchronous detection shown in FIG. 4 .
- the thick line indicates the waveform of the signal after passing through the band elimination filter 35
- the thin line indicates the waveform after synchronous detection.
- the band elimination filter 35 has an effect of reducing the noise to about one fifth.
- the thin line indicates the output angle error in the case where the notch filter is not used
- the thick line indicates the output angle error in the case where the notch filter is used.
- the noise can be further reduced by increasing the width of the notch by reducing the Q value of the notch filter.
- an excessively wide notch may affect the angle calculation loop, so that an optimum Q value has to be selected by taking these tradeoffs into account.
- the Q value preferably falls within a range of 0.5 to 5 and more preferably falls within a range of 0.8 to 1.0.
- the band elimination filter 35 that eliminates or reduces the low frequency noise (normal mode noise) component occurring due to the effect of the magnetic field produced by the motor and superposed on the resolver signals S 1 and S 2 is provided between the synchronous detection circuit 34 and the controller 36 in the angle calculation loop in the R/D converter 30 , and the noise occurring due to the effect of the magnetic field produced by the motor 20 can be eliminated.
- the output angle error of the RID converter 30 can be reduced.
- an angle detecting apparatus that comprises the R/D converter 30 , the resolver 10 and the excitation signal generating part 40 can accurately detect the angle of rotation of the motor 20 .
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- Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Engineering & Computer Science (AREA)
- Theoretical Computer Science (AREA)
- Transmission And Conversion Of Sensor Element Output (AREA)
- Control Of Electric Motors In General (AREA)
Abstract
Description
S2: sin αt sin ωt+cos α′t (1)
S1: cos αt sin ωt+sin α′t (2)
cos(α′t+φ)sin ωt (5)
Claims (5)
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
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JP2007-330399 | 2007-12-21 | ||
JP2007330399A JP4476321B2 (en) | 2007-12-21 | 2007-12-21 | RD converter and angle detection device |
Publications (2)
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US20090160687A1 US20090160687A1 (en) | 2009-06-25 |
US7768431B2 true US7768431B2 (en) | 2010-08-03 |
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US12/317,095 Active US7768431B2 (en) | 2007-12-21 | 2008-12-19 | R/D converter and angle detecting apparatus |
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US (1) | US7768431B2 (en) |
EP (1) | EP2073390B1 (en) |
JP (1) | JP4476321B2 (en) |
CA (1) | CA2646213C (en) |
Families Citing this family (13)
Publication number | Priority date | Publication date | Assignee | Title |
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JP4780223B2 (en) | 2009-08-06 | 2011-09-28 | 株式会社デンソー | Vehicle drive motor control device |
WO2011068196A1 (en) * | 2009-12-04 | 2011-06-09 | 本田技研工業株式会社 | Resolver digital converter |
JP5422401B2 (en) * | 2010-01-07 | 2014-02-19 | 川崎重工業株式会社 | Resolver signal conversion apparatus and method |
JP2011153864A (en) * | 2010-01-26 | 2011-08-11 | Oriental Motor Co Ltd | Rotational position detection device, and motor driving system using the same |
JP2011232199A (en) * | 2010-04-28 | 2011-11-17 | Tamagawa Seiki Co Ltd | Resolver signal conversion method |
JP5671920B2 (en) * | 2010-10-04 | 2015-02-18 | 日産自動車株式会社 | Motor drive device |
JP6107557B2 (en) | 2013-09-12 | 2017-04-05 | 株式会社ソシオネクスト | Angle detection device and angle detection method |
US10317245B2 (en) | 2014-01-27 | 2019-06-11 | Ford Global Technologies, Llc | Resolver excitation frequency scheduling for noise immunity |
JP6432037B2 (en) * | 2014-10-30 | 2018-12-05 | パナソニックIpマネジメント株式会社 | Resolver angular position detector |
JP6796726B1 (en) * | 2019-03-01 | 2020-12-09 | 東芝三菱電機産業システム株式会社 | Resolver signal processing device, drive device, resolver signal processing method, and program |
JP2021096198A (en) * | 2019-12-19 | 2021-06-24 | 多摩川精機株式会社 | R/d conversion method and r/d converter |
CN112152542B (en) * | 2020-09-24 | 2022-04-19 | 深圳市兆威机电股份有限公司 | Hall signal processing method and device, motor controller and storage medium |
CN114485736A (en) * | 2020-11-12 | 2022-05-13 | 华大半导体有限公司 | Decoding system and method of rotary transformer and electronic equipment |
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US4468745A (en) * | 1980-03-21 | 1984-08-28 | Trallfa Underhaug A/S | Device for position measurement |
US4857926A (en) * | 1987-08-25 | 1989-08-15 | Honeywell Inc. | Phase-responsive angular tracking device |
JP2000353957A (en) | 1999-06-11 | 2000-12-19 | Tamagawa Seiki Co Ltd | Digital conversion method for analog signal |
JP2003153496A (en) | 2001-11-12 | 2003-05-23 | Matsushita Electric Ind Co Ltd | Motor control unit |
JP2006058232A (en) | 2004-08-23 | 2006-03-02 | Sony Corp | Processor for angle detection signal |
JP2007114165A (en) | 2005-10-24 | 2007-05-10 | Nippon Reliance Kk | Device and method for detecting position of moving object |
-
2007
- 2007-12-21 JP JP2007330399A patent/JP4476321B2/en active Active
-
2008
- 2008-12-11 CA CA2646213A patent/CA2646213C/en active Active
- 2008-12-12 EP EP08021615A patent/EP2073390B1/en active Active
- 2008-12-19 US US12/317,095 patent/US7768431B2/en active Active
Patent Citations (7)
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US4468745A (en) * | 1980-03-21 | 1984-08-28 | Trallfa Underhaug A/S | Device for position measurement |
US4857926A (en) * | 1987-08-25 | 1989-08-15 | Honeywell Inc. | Phase-responsive angular tracking device |
JP2000353957A (en) | 1999-06-11 | 2000-12-19 | Tamagawa Seiki Co Ltd | Digital conversion method for analog signal |
US6278388B1 (en) * | 1999-06-11 | 2001-08-21 | Tamagawa Seiki Kabushiki Kaisha | Method of converting an analog signal to digital signal by digitalizing error deviation |
JP2003153496A (en) | 2001-11-12 | 2003-05-23 | Matsushita Electric Ind Co Ltd | Motor control unit |
JP2006058232A (en) | 2004-08-23 | 2006-03-02 | Sony Corp | Processor for angle detection signal |
JP2007114165A (en) | 2005-10-24 | 2007-05-10 | Nippon Reliance Kk | Device and method for detecting position of moving object |
Non-Patent Citations (3)
Title |
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Extended European Search Report issued Feb. 1, 2010 for corresponding EP patent application No. 08 021 615.3. |
Office Action for priority application JP 2007-330399 issued Oct. 6, 2009. |
Yim et al., "A Resolver-to-Digital Conversion Method for Fast Tracking," IEEE Trans. on Industrial Electronics, vol. 39, No. 5, Oct. 1992, pp. 369-377. |
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Publication number | Publication date |
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US20090160687A1 (en) | 2009-06-25 |
CA2646213C (en) | 2012-10-23 |
JP2009150826A (en) | 2009-07-09 |
EP2073390B1 (en) | 2011-05-18 |
EP2073390A3 (en) | 2010-03-03 |
CA2646213A1 (en) | 2009-06-21 |
JP4476321B2 (en) | 2010-06-09 |
EP2073390A2 (en) | 2009-06-24 |
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